Proteins of the corneal stroma: importance in visual function

Abstract

The human cornea, consisting of five layers, is the transparent tissue that refracts and transmits light to the lens and retina, providing about two thirds of the refractive power of the eye. The stroma layer comprises nearly 90 % of the thickness of the cornea and thus plays a pivotal role in normal visual function. The bulk of this layer is constituted by proteins in the extracellular martrix secreted by the corneal epithelial, stroma, and endothelial cells. Clinical research has shown that corneal stroma diseases are common and involve conditions such as infections, injuries, and genetic defects, which cause severe visual disturbances or even blindness. To improve our understanding of the basic molecular mechanisms involved in the physiological and pathological activities of the corneal stroma, its proteins have been brought into the limelight to determine their crucial and irreplaceable roles. The data presented in a previous study have demonstrated the presence of 1679 proteins in the stroma, and this data set has subsequently been perfected by utilizing a highly sensitive isobaric peptide-labeling approach. According to their manifestations, these proteins can be classified as a gel-like organic material composed of proteoglycans, enzymes, and hemocyanin-binding proteins and a network of filaments composed of collagen, elastin, keratin, vimentin, and interconnected filaments comprising fibronectin and laminin. The aim of this review is to describe some corneal stroma proteins by highlighting their major functions and valuable applications in ophthalmologic research toward the better characterization and treatment of eye diseases.

Variations in the endogenous fluorescence of rabbit corneas after mechanical property alterations

“…It follows that a spectral analysis considering known fluorophores suggests that the spectral features of pyridoxine are the closest to the 290-/390-nm fluorescence observed herein. Although the molecules mentioned above are in principle present in the cornea, 18 the literature on eye autofluorescence that we are aware of studied the lens only from 350-to 430nm excitation wavelengths or the cornea at 446-nm excitation wavelength. 14,19,20 These studies concentrated on the relationship between eye autofluorescence and metabolism, for example, the accumulation of lipofuscin in age-related macular degeneration.…”

Oxidative Stress in the Pathogenesis of Corneal Endothelial Dystrophies and Other Corneal Diseases

“…The principal function of the cornea is to refract light to the lens and the retina [25]. Constant exposure of the cornea to ultraviolent rays leads to the production of ROS in cornea.…”

Clinical Trials of Limbal Stem Cell Deficiency Treated with Oral Mucosal Epithelial Cells

“…The stroma creates 80% of the cornea thickness and is composed mainly of water and proteins. Xuan et al [3] identified 1679 different types of proteins present in the stroma. Keratinocytes were detected in the stroma, which are involved in the secretion of extracellular matrix, which is essential for maintaining the transparency of the cornea [4].…”